Probe navigation method and device and defect inspection device

ABSTRACT

A probe navigation method, a navigation device, and a defect inspection device wherein in a charged particle beam system provided with probes for electrical characteristics evaluation, probing can be easily carried out regardless of the equipment user&#39;s level of skill are provided. To attain this object, probes and a test piece stage on which a test piece is placed are driven by independent driving means. Further, a large stage driving means which integrally drives the probes and the test piece stage is provided. In addition, CAD navigation is adopted. This enhances the equipment users&#39; convenience during probing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of application Ser. No.11/018,356, filed Dec. 22, 2004, the disclosure of which is herebyincorporated by reference.

CLAIM OF PRIORITY

The present application claims priority from Japanese applications JP2003-426169 filed on Dec. 24, 2003 and JP 2004-297115 filed on Oct. 12,2004, the contents of which are hereby incorporated by reference intothis application.

FIELD OF THE INVENTION

The present invention relates to a method for positioning probes in adefect inspection device which measures the electrical characteristicsof electronic devices using the minute probes, and to a defectinspection device using the positioning method.

BACKGROUND OF THE INVENTION

Varied inspection equipment is conventionally known for detectingelectrical defects in minute electronic circuits formed on asemiconductor chip. Such inspection equipment includes EB tester(Electron Beam tester) and prober device. The EB tester is a device fordetecting points of electrical defect in LSIs. This detection is carriedout by irradiating a point of measurement with an electron beamutilizing the following phenomenon: the amount of secondary electronemission from the point of measurement when irradiated with an electronbeam varies depending on the value of voltage of the point ofmeasurement. The prober device is a device for measuring the electricalcharacteristics of LSIs. This measurement is carried out by bringing aplurality of mechanical probes, disposed in correspondence with thepositions of pads for characteristics measurement on LSIs, into contactwith the measuring pads. In such an EB tester or prober device, theequipment operator manually confirms the probing positions of probeswhile viewing images, such as optical microscope images and SEM(Scanning Electron Microscope) images of wiring.

Recently, circuit patterns formed on semiconductor devices, such asLSIs, have been increasingly micro miniaturized and complicated. It isbecoming difficult to move probes to optimum probing positions in ashort time. To cope with this, techniques designated as CAD navigationhave been developed for shortening the time required for probing. TheCAD navigation is such that the wiring layout of a semiconductor deviceis displayed in alignment with the actual image of the semiconductordevice viewed by the equipment operator during probing. For example,Patent Document 1 discloses an example of an EB tester using CADnavigation. Patent Document 2 discloses an example in which CADnavigation is applied to FIB (Focused Ion Beam) processing equipment. Inthe technique disclosed in Patent Document 2, a secondary electron imageproduced by a test piece to be processed when the test piece isirradiated with a focused ion beam is observed. In this way, anappropriate position of ion beam irradiation is determined.

The techniques disclosed in Patent Documents 1 and 2 are those f orcarrying out defect inspection on semiconductor chips. There is alsodemand for carrying out defect inspection on wiring patterns onsemiconductor wafers before they are formed into chips. Patent Document3 discloses a technique for moving probes to positions of FIB processingso as to move a processed piece, obtained by FIB processing, from apredetermined position in the wiring pattern on a wafer by the probes.More specifically, FIB processing equipment is provided with a probeinformation screen for displaying the image of the tip of a probe. Theequipment user specifies a target location to which the probe is to bemoved on the probe information screen. The equipment computes thedifference between the inputted target location and the present positionof the tip of the probe, and moves the probe to the target location.Thus, when the probe is moved to a target location on a wafer, a burdenon the equipment user can be lessened.

[Patent Document 1] Japanese Patent Laid-Open No. H7(1995)-240446

[Patent Document 2] Japanese Patent Laid-Open No. H8(1996)-54447

[Patent Document 3] Japanese Patent Laid-Open No. 2000-147070

SUMMARY OF THE INVENTION

Recently, wiring patterns formed on semiconductor wafers have beenincreasingly microminiaturized. The positioning accuracy demanded inprobing is presently on the order of nm. It is difficult to automatizeprobing with such high accuracy with the present technology, and thereis no other choice but to manually perform probing operation. Further,the size of wafers used in the manufacturing processes for semiconductordevices has been increased as compared with conventional wafers. Thisincreases a burden on equipment users during probing operation. This isbecause of the following: increase in the size of wafers means increasein the frequency of changing the magnification of an image for probecheck when a probe is moved. Each time the magnification is changed, theequipment user must move the probe so that the probe will come into thefiled of view embracing the image. To lessen a burden on the equipmentuser, CAD navigation can be introduced. However, it cannot be said thatthe conventional equipment has a configuration optimum for theintroduction of CAD navigation.

Some examples will be taken. The equipment disclosed in Patent Document2 uses CAD navigation only for checking whether pads for measurement arepositioned directly under a probe card or not. Patent Document 2 doesnot disclose a technique for positioning probes in arbitrary locationson a wafer. Since Patent Document 1 relates to EB tester, it does notdisclose a technique related to the movement of probes. Patent Document3 does not originally involve the disclosure of CAD navigation.

Consequently, an object of the present invention is to provide a probenavigation method and device and a defect inspection device wherein in acharged particle beam system equipped with probes for electricalcharacteristics evaluation, probing can be easily carried out regardlessof the equipment user's level of skill.

According to the present invention, a charged particle beam systemequipped with at least one probe for electrical characteristicsevaluation comprises: a test piece stage for holding a test piece; ameans for acquiring the charged particle beam image of the test piece; afirst driving means for driving probes; a second driving means formoving the test piece stage; a third driving means which drives the testpiece stage and the probes as integrated into one; and a controllingmeans for controlling these three driving means. This charged particlebeam system attains the above object by the following operation:according to set values inputted by the equipment user or establishedbeforehand, it operates the third driving means so that at least oneprobe will come into the field of view embracing the charged particlebeam image. Further, it moves the test piece stage so that the probinglocation will come into the field of view embracing the charged particlebeam image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing illustrating an example of the configuration of adefect inspection device.

FIG. 2A is a flowchart illustrating part of the basic flow of theprobing operation using the defect inspection device illustrated in FIG.1.

FIG. 2B is a flowchart illustrating part of the basic flow of theprobing operation using the defect inspection device illustrated in FIG.1, subsequent to the flowchart in FIG. 2A.

FIG. 2C is a flowchart illustrating part of the basic flow of theprobing operation using the defect inspection device illustrated in FIG.1, subsequent to the flowchart in FIG. 2B.

FIG. 2D is a flowchart illustrating part of the basic flow of theprobing operation using the defect inspection device illustrated in FIG.1, subsequent to the flowchart in FIG. 2C.

FIG. 3 is a drawing illustrating examples of a SEM image at highmagnification and a CAD image at high magnification displayed on thedevice illustrated in FIG. 1.

FIG. 4 is a drawing illustrating the SEM image at high magnification andthe CAD image at high magnification illustrated in FIG. 3 when they aresuperimposed.

FIGS. 5A and 5B are drawings illustrating an example in which the areacorresponding to a CAD image at high magnification is indicated by anarrow in a CAD image at low magnification.

FIG. 6 is a drawing illustrating an example of a defect inspectionsystem in which one CAD WS is shared among a plurality of defectinspection devices.

FIG. 7 is a drawing illustrating another example of the configuration ofa defect inspection device.

FIG. 8 is a drawing illustrating examples of a SEM image, EBAC image,and CAD image displayed on the device illustrated in FIG. 7.

FIGS. 9A to 9D are a drawing illustrating another example of theconfiguration of a defect inspection device and detail drawings thereof.

FIG. 10A is a block diagram of a defect inspection device in a fourthembodiment.

FIG. 10B is a block diagram of the defect inspection device in thefourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereafter, description will be given to embodiments of the presentinvention, referring to the drawings. The term “probe” found in thefollowing description refers to a mechanical probe, but it is not usedto refer to any other probe, such as electron beam probe.

First Embodiment

Description will be given to a first embodiment which involves a defectinspection device with mechanical probes for electrical characteristicsevaluation incorporated into the test piece chamber of SEM. FIG. 1illustrates an example of the configuration of a defect inspectiondevice in which a probe navigation method of the first embodiment isimplemented. FIGS. 2A to 2D illustrate the basic flow of inspectioncarried out using the inspection device of the first embodiment. First,the configuration of the inspection device will be described referringto FIG. 1.

An electron gun 101 constitutes an irradiation optical system forirradiating a test piece 118 with a primary electron beam 103 andscanning it. Therefore, the electron gun 101 in the first embodimentmeans a system including all the constituent elements required forelectron beam irradiation. Such constituent elements include an electronsource which generates an electron beam, and a deflector lens forapplying a beam from point to point. A vacuum chamber partition wall 102separates an area under atmospheric pressure and an area in vacuum. Theoperation of the electron gun 101, including the electron beamextraction voltage of the electron source and the applied voltage to thedeflector lens, is controlled by an electron gun controller 116.

Secondary electrons 105 produced by a test piece 118 under test as theresult of irradiation of the primary electron beam 103 are detected by asecondary electron detector 104. The secondary electron detector isconstituted as follows: its sensor portion which actually detectselectrons is disposed inside the partition wall 102, and its baseportion to which a wire for power supply connection and the like areconnected is protruded out of the partition wall. Mechanical probes 106are brought into contact with predetermined areas in a test piece undertest, and are held by attachments 107. Probe driving means 108 are formoving the attachments 107 to desired locations, and move the mechanicalprobes 106 together with the attachments 107 to desired locations.

A test piece 118 to be actually inspected for defect is held on a testpiece stage 109. The test piece stage 109 is in turn held on a testpiece stage driving means 110. The test piece stage 109 and the testpiece stage driving means 110 are collectively designated as DUT stage.The DUT stage and the probe driving means 108 are formed on a largestage 111. The large stage 111 is provided with driving means formovement in the x, y (in-plane), and z (vertical) directions. The largestage 111 is capable of integrally driving the DUT stage and the probedriving means 108. One of the features of the first embodiment is thatthe DUT stage and the probe driving means 108 are integrally formed onthe large stage 111. An important aspect of the spirit of the presentinvention is as follow: the inspection device is so constituted that atest piece 118 under test and the mechanical probes 106 can beindependently and integrally moved. The large stage 111 is in turndisposed on a base 112. Since the large stage 111 is provided with thedriving means for movement in the z (vertical) direction, the followingadvantage is brought: the large stage 111 is moved down in the zdirection before the large stage 111 is moved in the x or y direction.Thereby, interference between the test piece 118, mechanical probes 106,or attachments 107 and the tip of the electron gun 101 can be avoided.When the first embodiment is actually used to carry out SEM observation,the following advantage is brought: the large stage 111 is moved up inthe z direction, and thereby the working distance between the tip of theelectron gun 101 and the test piece 118 can be reduced. As a result, thespatial resolution of SEM can be enhanced. In the first embodiment, thedriving means for movement in the z direction is incorporated into thelarge stage 111. Instead, it may be incorporated into the test piecestage driving means 110 and the probe driving means 108, or all of thelarge stage 111, test piece driving means 110, and probe driving means108. In these cases, the same effect is obtained.

A movement measuring element (not shown) may be incorporated into all orany of the large stage 111, test piece stage driving means 110, andprobe driving means 108. For the movement measuring element, forexample, a linear scale or an encoder can be used. This brings thefollowing advantages: the accuracy of movement of probes, test piece,and stages can be enhanced and quantified. Since the movement can bemore accurately measured with the movement measuring elements, CADnavigation can be more accurately carried out.

The test piece stage 109 and the attachments 107 are connected to anelectrical characteristics measuring instrument 113. The probes 106 andthe attachments 107 are brought into contact with a test piece 118 anddetect electrical signals; therefore, they are electrically floated withrespect to the other elements than the electrical characteristicsmeasuring instrument 113. The electrical characteristics measuringinstrument measures mainly the current/voltage characteristic of a testpiece 118 detected by the mechanical probes 106, and computes desiredcharacteristic values from it. Such characteristic values include, forexample, the resistance value, current value, and voltage value ofpoints probed by the mechanical probes 106. In case of an analysis of asemiconductor wafer, for example, a semiconductor parameter analyzer isused for the electrical characteristics measuring instrument 113. Thereason why the electrical characteristics measuring instrument 113 andthe test piece stage 109 are connected with each other is as follows:there are cases where the test piece placement face of the test piecestage 109 is provided with a feed plug for applying current or voltageto test pieces.

The characteristic values obtained as the result of measurement by theelectrical characteristics measuring instrument 113 is transmitted to acontrol computer 114 through a transmission line. The control computer114 carries out more sophisticated analyses based on the transmittedinformation. For example, the control computer analyzes measured valuesand determines whether the point of measurement is defective or normal.The control computer 114 is provided with a storing means 115, such asoptical disk, hard disk, or memory, and is capable of storing themeasured electrical characteristics. The control computer 114 also playsa role in controlling the operation of the entire defect inspectiondevice. For example, the operation of the electron gun controller 116,secondary electron detector 104, probe driving means 108, DUT stage, andlarge stage 111 is controlled by the control computer 114. For thispurpose, the control computer 114 is provided with the storing means 115for storing software for controlling connected components, and with aninputting means for the equipment user to input setting parameters.Examples of the inputting means include image displaying means fordisplaying operating screens and SEM images, keyboard, mouse for movinga pointer on an operating screen. The equipment user uses an appropriateinputting means to input the positional information and magnificationinformation of the target of probe movement and such information as thecontrast and brightness of images.

Data (hereafter, referred to as “CAD image data) on the wiring layout ofa test piece under test is stored in CAD WS (Workstation) 117. The WS117 is provided with an image displaying means for displaying wiringlayouts. The CAD WS 117 is connected to the control computer 114, andtransmits CAD image data to the control computer 114 as required.

In the first embodiment, the control computer 114 and the CAD WS 117 areconstituted as separate computers. Instead, they may be integrated andconstituted as a single computer. In addition, the electron guncontroller 116 may also be integrated and the three units may beconstituted as a single computer.

Next, description will be given to the operation of the defectinspection device illustrated in FIG. 1, referring to FIG. 2A to FIG.2D. When started, the device is brought into a state in which the devicewaits for the magnification of SEM image to be set. Then, the displayingscreen accompanying the control computer 114 displays a means forinputting the setting of magnification (Step 201). Examples of the meansfor inputting the setting of magnification include inputting means basedon icons or GUI. The equipment user inputs a magnification of SEMthrough the inputting means. The equipment user does not know where theprobes 106 are located on the large stage 111. Therefore, at Step 201,the equipment user usually inputs the lowest magnification of the SEM.When the tips of the probes are congregated in the relatively centralarea in the SEM field of view, a low magnification is acceptable. Thelow magnification here referred to is usually a magnification not higherthan 300 times. The controlling means 114 adjusts the conditions of theelectron gun 101 based on the inputted values, acquires a SEM image atthe inputted magnification, and displays the image on the displayingmeans (Step 202).

The equipment user visually checks whether the target location ofmeasurement on the test piece is embraced in the acquired SEM image ornot (Step 203). If not, the equipment user drives the large stage 111 tomove the test piece stage 109 into the field of view embracing the SEMimage (Step 204). Instead of moving the large stage 111, the equipmentuser may move the DUT stage itself to move the point of inspection intothe field of view embracing the SEM image. At Step 204, the point ofinspection indicated over the SEM image can look like a dot at the mostdepending on the size of the point of inspection. After confirming thatthe point of inspection is located in the field of view embracing theSEM image, the equipment user visually checks in turn the following:whether probes to be used in inspection on the test piece are located inthe field of view embracing the SEM image or not (Step 205). If theprobes are located in the field of view, the operation proceeds to Step207. If not, the equipment user drives the probe driving means 108 tomove all the probes to be used in inspection into the field of viewembracing the SEM image (Step 206). In this case, all the probes to beused in inspection are moved into the SEM field of view at Step 205 andStep 206. However, at least one of the probes only has to be located inthe field of view in some cases. Examples of such cases include: a casewherein it has been already known that the tips of all the probes to beused are located in proximity to one probe observed within the SEM fieldof view, for example, a case where inspection according to the presentinvention has been already carried out elsewhere on the test piece. Thisis the same with the following steps of the inspection.

After it has been confirmed that all the probes to be used are locatedin the field of view embracing the SEM image, the operation is performedat the following steps for displaying the SEM image at changedmagnification. First, the equipment user inputs a magnification of SEM(Step 207). As a means for inputting a magnification, the equipment useruses the inputting means displayed at Step 201 without change. Toinitiate probing operation, usually, a higher value of magnificationthan inputted at Step 201 is inputted to the inspection device at Step207. The control computer 114 adjusts the electron gun 101 and thesecondary electron detector 104 according to the inputted magnification,and acquires a SEM image at the inputted magnification (Step 208).

Thus, the image in which the area that looked like only a dot in theinitial SEM image at low magnification is displayed in magnified form.Therefore, the equipment user must carry out probing on the point ofinspection on the test piece in the SEM image at high magnification. Or,since a SEM image at high magnification is acquired, the point ofinspection which was originally located within the field of viewembracing the SEM image at low magnification can get out of the field ofview embracing the SEM image at the completion of Step 208. In somecases, probes also disappear from the field of view embracing the SEMimage. Consequently, it becomes necessary to identify the location ofinspection and carry out probe navigation. Therefore, description willbe given below to the flow of identifying the location of inspection andthe flow of probe navigation using CAD.

When a SEM image at high magnification is acquired, the control computer114 transmits a request for CAD image data of the point correspondingthe displayed SEM image to the CAD WS 117 (Step 209). The CAD WS 117transfers the requested CAD image data to the control computer 114 (Step210). The control computer 114 displays the CAD image on the displayingscreen. In addition, the control computer 114 displays on the displayingscreen a prompt to input a reference point for bringing CAD image andSEM image into correspondence with each other (Step 211). The equipmentuser inputs a reference point for correspondence between CAD image andSEM image to the control computer 114 through the inputting meansaccompanying the control computer 114. Possible methods for inputting areference point include clicking the pointer on some point on the CADimage and some point on the SEM image. The control computer 114 linksthe CAD image and the SEM image to each other based on the coordinateinformation (positional information) of the inputted reference point(Step 212). At the same time, the control computer 114 also links therespective magnification information.

After the link is provided between the CAD image and the SEM image atStep 212, the CAD WS 117 is brought into a state in which it waits forthe input of the positional information of the point of inspection, thatis, probing position, on the CAD image. For example, icons for inputtingprobing positions are displayed on the screen, or a message promptinginput is displayed on the screen (Step 213). When the equipment userspecifies probing positions, the CAD WS 117 transmits the coordinateinformation of the inputted probing positions to the control computer117 (Step 214). The control computer 114 converts the coordinateinformation of the probing positions, transmitted from the CAD WS 117,into coordinate information with respect to the SEM image (Step 215).

The operation of Step 215 can be implemented because the link ofcoordinate information was established between the SEM image and the CADimage at Step 211 and Step 212. Further, the control computer 114computes the movement of the DUT stage from the positional informationof the probing positions with respect to the obtained SEM image and thepresent positional information of the DUT stage (Step 216). The presentpositional information of the DUT stage can be computed based on thecoordinates of the reference position in the SEM image, specified by theequipment user at Step 212. After the completion of computation, thecontrol computer 114 moves the DUT stage by the computed amount.Thereby, the control computer 114 moves the points specified in the CADimage into the field of view embracing the SEM image at highmagnification (SEM image obtained at Step 208) (Step 217).

By carrying out the above-mentioned steps, the following can beimplemented when the magnification of the SEM image is increased: targetprobing positions can be automatically moved into the field of viewembracing the SEM image, and thus the effort that must be otherwise madeby the equipment user can be reduced.

At Step 218, the equipment user visually checks whether the probingpositions are embraced in the displayed SEM image. If not, the equipmentuser drives the DUT stage so that the probing positions will come intothe SEM field of view (Step 220). As the result of the operation of Step217, the probing positions must have moved to the vicinity of the fieldof view embracing the presently visible SEM image. Therefore, even ifthe equipment user searches for probing positions by him/herself, aburden on the equipment user can be lessened as compared withconventional cases. When the operation of Step 220 is performed, thefield of view embracing the SEM image is changed. Therefore, the CADimage must also be changed; however, the CAD image is automaticallyupdated by the inspection device.

The control computer 114 already holds the information of link betweenthe coordinates in the SEM image and those in the CAD image. Therefore,the control computer 114 computes the movement and direction of movementof the DUT stage, moved through the operation by the equipment user.Then, the control computer 114 requests the CAD WS 117 to transmit CADdata corresponding to the coordinates of the SEM image presentlydisplayed. The CAD WS 117 selects appropriate CAD data based on thecoordinate information of CAD data, transmitted from the controlcomputer 114, and transfers it to the control computer 114 (Step 221).The control computer 114 displays the transmitted CAD data on thedisplaying screen in the form of image, and completes the operation ofupdating the CAD image (Step 222).

As mentioned above, the defect inspection device of the first embodimentis provided with a function of updating the displayed CAD image inaccordance with change in the field of view embracing the SEM image.With the defect inspection device of the first embodiment, therefore, aburden on the equipment user is significantly lessened during probing.

If the probing positions are embraced in the field of view embracing theSEM image, next, the equipment user checks whether all the probes to beused in inspection are located in the field of view embracing the SEMimage or not (Step 219). In the first embodiment, the operation of Step219 is also visually checked by the equipment user. If all the probesare located in the field of view embracing the SEM image, the operationproceeds to Step 223. If not, the equipment user operates the probedriving means 108 so that the tips of all the probes to be used willcome into the field of view embracing the SEM image (Step 224). Thereare cases where only one mechanical probe 106 is used in defectinspection, but a plurality of probes are often required. Some exampleswill be taken. If voltage is applied though a feed plug, the contactresistance of a point of probing can be inspected by bringing a probeinto contact only with the point. However, to examine I/Vcharacteristics or the like, at least two mechanical probes arerequired, and to examine the characteristics of a transistor, at leastthree probes are required.

In FIG. 1, the defect inspection device of the first embodiment looks touse only two mechanical probes 106. In actuality, however, more than twomechanical probes are used. To switch from a SEM image at lowmagnification to a SEM image at high magnification in stages, thefollowing procedure is taken: at the completion of the processing ofStep 219, the magnification of the SEM image is changed, and theoperation goes back to Step 218 and the same processing is performedagain. In this case as well, the displayed CAD image is automaticallyupdated to the magnification of the SEM image.

When all the probes to be used are positioned in the field of viewembracing the SEM image, the displaying screen of the control computer114 shows the SEM image and the CAD image in superimposition (Step 223).Viewing the displayed SEM image and CAD image, the equipment user movesthe mechanical probes 106, and brings the probes into contact withpoints of inspection. When all the probes are brought into contact, themeasurement of the electrical characteristics of the points of probingcan be started (Step 225).

As mentioned above, the SEM image and the CAD image are displayed insuperimposition at Step 223. However, there can be misalignment betweenthe SEM image and the CAD image because of the machine accuracy of theDUT stage. A method for eliminating this misalignment will be describedreferring to FIG. 2D. Following Step 222, the control computer 114displays the SEM image and the CAD image in superimposition. If there ismisalignment at this time, the misalignment can be corrected by theequipment user (Step 226). The concrete procedure for misalignmentcorrection is the same as Step 211 and Step 212 in FIG. 2B. In thiscase, however, the magnification is higher than in Step 211 and Step212; therefore, the positional misalignment can be more accuratelycorrected. More specific description will be given. The control computer114 displays on the displaying screen a prompt to input a referencepoint for bringing the SEM image and the CAD image into correspondencewith each other. The equipment user inputs a reference point forcorrespondence between the SEM image and the CAD image to the controlcomputer 114 by the inputting means accompanying the control computer114. Possible methods for inputting a reference point include clickingthe pointer on some point on the SEM image and some point on the CADimage. The control computer 114 corrects the misalignment between theSEM image and the CAD image based on the coordinate information(positional information) of the inputted reference point. At the sametime, the control computer 114 may also update the respective linkinformation associated with magnification information. In FIG. 2D, Step226 is placed next to Step 222. Instead, Step 226 may be placed next toStep 223.

The foregoing is a description of the basic flow of probing used wheninspection is carried out using the inspection device illustrated inFIG. 1. To change a probing position, the processing of FIGS. 2A to 2Dneed not be performed again from the beginning. The equipment userdrives the DUT stage, and thereby brings the probing position into thefield of view embracing the SEM image. Only the test piece can be movedindependently of the probes by driving the DUT stage. Therefore, thepoint of inspection can be moved with the correlation maintained betweenthe tips of the mechanical probes 106 and the primary electron beam 103.Thus, provision of the test piece stage driving means 110 illustrated inFIG. 1 obviates necessity for performing the processing of FIGS. 2A to2D again from the beginning. The equipment users' convenience isdramatically enhanced as compared with conventional charged particlebeam systems.

Of the flows illustrated in FIGS. 2A to 2D, the information of the stepscarried out by the inspection device is all stored in the storing means115 of the inspection device, illustrated in FIG. 1, as software forsequence control.

Item (a) of FIG. 3 illustrates an example of a SEM image at highmagnification, and Item (b) of FIG. 3 illustrates an example of the CADimage of the point corresponding to the SEM image under Item (a) of FIG.3. The drawing under Item (a) of FIG. 3 shows the tips of fourmechanical probes 106, a semiconductor wafer 118 as a test piece, plugs301 which appear in the wiring pattern formed on the wafer. The imageillustrated under Item (a) of FIG. 3 corresponds to the SEM imagedisplayed on the displaying screen of the control computer 114 when Step219 in the processing illustrated in FIG. 2C is completed. If all theprobes are originally located in the field of view embracing the SEMimage at high magnification, the same SEM image is also displayed at thecompletion of Step 208.

The drawing under Item (b) of FIG. 3 illustrates the layout of thewiring pattern on the wafer which cannot be observed in the SEM image inreality. The drawing includes a wafer 118 and plugs 302 which correspondto the plugs 301 in the drawing under Item (a) of FIG. 3. The areasencircled with dotted lines indicate that wiring 303 is formed there.The wiring 303 is completely invisible in the SEM image under Item (a)of FIG. 3. Therefore, if a defect is, for example, a break in the wiring303, the following procedure must be taken in conventional inspectionequipment which does not display CAD images: a skilled equipment userdetermines the probing position while moving the CAD image in accordancewith the movement of the field of view embracing the SEM image.Meanwhile, in this embodiment, the SEM image at high magnification andthe CAD image are displayed together on the control computer screen, asillustrated under Item (b) of FIG. 3. Therefore, the equipment users'convenience during probing is dramatically enhanced as compared withconventional cases.

FIG. 4 illustrates the way a SEM image at high magnification and a CADimage are displayed in superimposition. This image corresponds to theimage displayed on the control computer screen when Step 223 in the flowillustrated in FIG. 2C is completed. Displaying the CAD image and theSEM image in superimposition further enhances the equipment users'convenience when the user finally brings the probes into contact.

FIGS. 5A and 5B illustrate an example in which a CAD image at lowmagnification and a CAD image at high magnification are displayedtogether on the control computer 114 screen. FIG. 5A illustrates a CADimage at low magnification. It may be considered as a CAD imageembracing the area substantially corresponding to the field of viewembracing the SEM image at the lowest magnification set at Step 202 inFIG. 2A. The CAD image at high magnification illustrated in FIG. 5B maybe considered as a CAD image embracing the area corresponding to thefield of view embracing the SEM image acquired at Step 208 in FIG. 2A. ACAD image at such a level of magnification as illustrated in FIG. 5Ashows an overall view of the wiring layout on a wafer. In FIG. 5A, forexample, a circuit 502 to be measured as well as a peripheral circuit501 and related circuits 503 are displayed on the screen.

In a CAD image on the scale illustrated in FIG. 5A, a CAD image on thescale illustrated in FIG. 5B only looks like a dot. Consequently, anarrow 504 indicating the area illustrated in FIG. 5B is displayed overthe CAD image at low magnification (wide-area CAD image). Thus, theequipment users' convenience is enhanced when the user manually movesprobes. This function is used, for example, when after the completion ofmanual probing of Step 225 in FIG. 2D, the user moves the SEM image tothe next point of inspection. More specific description will be given.When the movement to the next point of inspection is great, for example,the following operation is performed: the magnification of the SEM imageis once lowered to display a SEM image at low magnification, and thelarge stage is driven. In this case, a wide-area CAD image including thearea illustrated in FIG. 5B, or the target position is called up fromthe CAD WS 117, and is displayed on the control computer 114.

The arrow 504 is displayed over the wide-area CAD image. Therefore, theequipment user manually operates the large stage or the DUT stage,aiming at the dot indicated by the arrow. Thereby, the equipment userbrings the point of inspection into the field of view embracing the SEMimage at low magnification. As long as the link is established betweenthe SEM image and the CAD image, the arrow 504 may be displayed incombination with the SEM image at low magnification. What is marked withreference numeral 504 is not limited to arrow, and it may be constitutedin any manner, including pointer and icon, as long as it is a means forindicating the area including the point of inspection. To make itpossible to call up wide-area CAD images from the CAD WS 117, a meansfor calling up wide-area CAD images only has to be displayed on thedisplaying means of the control computer 114. Possible means for callingup the images include an icon indicating wide-area CAD image.

Second Embodiment

Description will be given to a second embodiment which involves a defectinspection system so constituted that CAD WS is shared among a pluralityof defect inspection devices or failure analyzers. FIG. 6 schematicallyillustrates a defect inspection system. A plurality of (three) defectinspection devices 601 are connected to CAD WS 602 through communicationlines 603. The second embodiment is on the assumption that the internalstructure of the three defect inspection devices is the same as thedefect inspection device illustrated in FIG. 1. However, any otherequipment may be used for this purpose. The three units may beconstituted as a combined defect analyzing system comprising a defectinspection device and a failure analyzer. For example, the followingcombination is acceptable: one of the three units is a defect inspectiondevice illustrated in FIG. 1, and the other two units are a focused ionbeam system and a transmission electron microscope. In case of thecombined defect analyzing system in the second embodiment, the threeunits are independent vacuum systems. Respective vacuum devices areconnected to the three units, and these vacuum devices are connected toone another through vacuum transport systems (not shown). In this case,test pieces can be transported between the devices without being exposedto the atmospheric air. This produces the effect of reducing theinfluence of test piece contamination in the air.

The CAD WS 602 is a device which stores all the wiring layouts formed ontest pieces under test, and is very expensive. Therefore, one CAD WS 602is shared, as illustrated in FIG. 6, and thereby the cost incurred whenthe system is built can be reduced. Further, the scale of the system canbe increased only by adding a defect inspection device one by one.Therefore, this is a constitution highly effective in ensuring thescalability of the defect inspection system.

Third Embodiment

Description will be given to a third embodiment. This is another exampleof the defect inspection device in which mechanical probes forelectrical characteristics evaluation are mounted inside the test piecechamber of SEM. FIG. 7 illustrates an example of the configuration of adefect inspection device in which the probe navigation method of thethird embodiment is carried out. This configuration is substantially thesame as the configuration of the defect inspection device of the firstembodiment, illustrated in FIG. 1. Therefore, description will be givenonly to a difference between them.

The difference between the device in FIG. 1 and that in FIG. 7 is thepresence of an insulating plate 701. The insulating plate 701 is mountedso that it is sandwiched between the test piece stage 109 and the testpiece stage driving means 110. Thus, test pieces are electricallyinsulated from the vacuum chamber partition wall 102, test piece stagedriving means 110, and the like.

This constitution enables an EBAC (Electron Beam Absorption Current)method for inspecting fine wiring formed on a test piece 118 for faultyelectrical continuity.

The test piece stage 109 and the attachments 107 are connected to theelectrical characteristics measuring instrument 113. The electricalcharacteristics measuring instrument 113 measures mainly the absorptioncurrent at the test piece 118 detected by the probes 106.

For analyses of faulty electrical continuity in the wiring ofsemiconductor devices, for example, a high sensitivity current detectoris used as the electrical characteristics measuring instrument 113. Thereason why the electrical characteristics measuring instrument 113 andthe test piece stage 109 are connected with each other is as follows:there are cases where the test piece placement face of the test piecestage 109 is provided with a feed plug for applying current or voltageto test pieces 118.

The value of absorption current measured by the electricalcharacteristics measuring instrument 113 is transmitted to the controlcomputer 114 through a transmission line. The control computer 114 takesthis value as a luminance signal, and produces a display on the monitorscreen of the control computer 114 in synchronization with the scanningcycle of the primary electron beam 103 of SEM. Thereby, the controlcomputer 114 can form EBAC (Electron Beam Absorption Current) imagesembraced in the same field of view as SEM images are embraced.

Next, description will be given to EBAC image acquisition with theconstitution of the third embodiment and a method for estimating thelocation of a break based thereon. The description will be givenreferring to FIG. 7 and FIG. 8.

As an example, it is assumed that fine wiring is installed in a testpiece 118, and a plurality of metal plugs connected to this wiring areexposed at the surface of the test piece 118. When this is observedunder an ordinary SEM, the SEM image illustrated under Item (a) of FIG.8 is obtained. At this time, the CAD image corresponding to the SEMimage area illustrated under Item (a) of FIG. 8 is obtained, asillustrated under Item (c) of FIG. 8. At this time, the method describedin detail in connection with the first embodiment is used. Based on thisCAD image information, the probe 106 is brought into contact with anarbitrary plug. In this state, the primary electron beam 103 emittedfrom the electron gun 101 is applied to the surface of the test piece118 from point to point. Usually, the intensity of the secondaryelectrons 105 emitted at this time is taken as a luminance signal, and adisplay is produced on the screen in synchronization with the scanningcycle of the primary electron beam 103. Displayed is the SEM imageillustrated under Item (a) of FIG. 8. In the third embodiment, the valueof absorption current at the test piece 118 detected by the probe 106 istaken as a luminance signal in place of the intensity of secondaryelectrons. Thereby, the EBAC image illustrated under Item (b) of FIG. 8is obtained. If a break 804 exists in the internal wiring 803 connectingthe plug 801 and the plug 802 at this time, the absorption currentabsorbed at the plugs 801 is not detected by the probe 106. Therefore,the plugs 801 are not displayed in the EBAC image. In the imageillustrated under Item (b) of FIG. 8, the plugs 801 are indicated bywhite dotted-line circle to indicate their positions. In reality,however, nothing is observed in the EBAC image. The absorption currentabsorbed at the plug 802 is detected by the probe 106, and thus it isbrightly displayed in the EBAC image. The internal wiring 803 is notseen at all in the SEM image illustrated under Item (a) of FIG. 8.Therefore, if defect is the break 804 in the internal wiring 803, forexample, the following procedure must be taken with conventionalinspection equipment which does not display CAD images: a skilledequipment user determines the position of probing while moving the CADimage in accordance with the movement of the fields of view embracingthe SEM image and the EBAC image, and estimates the location of thebreak. Meanwhile, in this embodiment, the SEM image, EBAC image, and CADimage are displayed together on the control computer screen, asillustrated under Item (c) of FIG. 8. Thereby, the equipment users'convenience during probing is dramatically enhanced as compared withconventional cases.

The defect inspection device of the third embodiment is provided with afunction of updating the displayed CAD image in accordance with changein the fields of view embracing the SEM image and the EBAC image. Thisupdating is carried out by the same method as described in detail inconnection with the first embodiment. Therefore, with the defectinspection device of the third embodiment, a burden on the equipmentuser is significantly lessened during probing.

The value of absorption current measured by the probes 106 or the testpiece stage 109 in the third embodiment is often very small. For thisreason, detected signals can be influenced and deteriorated by noise. Inthis case, the following procedure can be taken instead of connectingthe test piece stage 109 and the attachments 107 directly to theelectrical characteristics measuring instrument 113: a preamplifier (notshown) is placed in the wiring between the test piece stage 109 and theattachments 107, and the electrical characteristics measuring instrument113 in proximity to the test piece 106 as much as possible. Then,microcurrent detected by the probes 106 or the test piece stage 109 isamplified into a voltage signal, and then transmitted to the electricalcharacteristics measuring instrument 113. Thus, the influence of thenoise of microcurrent can be reduced.

In the third embodiment, there are cases where only one probe 106 isused in defect inspection. There are cases where a plurality of probesare required as in the first embodiment. For example, when a pluralityof pieces of wiring are inspected for break or on like occasions, thesepieces of wiring can be inspected at a time by probing a plurality ofplugs.

In FIG. 7, the defect inspection device of the third embodiment looks touse only two mechanical probes 106. In actuality, however, more than twoprobes are used sometimes.

In the third embodiment as in the first embodiment, the SEM image andthe CAD image or the EBAC image and the CAD image can be displayed insuperimposition (not shown). Thereby, the equipment users' convenienceis further enhanced when the user finally manually brings probes intocontact and estimates the location of a break.

In the third embodiment as in the first embodiment, an arrow indicatingan area can be displayed over the CAD image at low magnification (notshown). Thereby, the equipment users' convenience can be enhanced whenthe user manually moves the probes.

In the third embodiment, SEM images and EBAC images can be obtained.These images can be displayed on the image displaying means provided tothe control computer 114. At this time, the operating screen of theimage displaying means provided to the control computer 114 can displayall or any of the SEM image, EBAC image, and CAD image. If the operatingscreen is provided with icons for changing the screens, various types ofdisplay can be implemented. For example, arbitrary images can beselectively displayed, all displayed, or displayed in superimposition.

Fourth Embodiment

A fourth embodiment, or another embodiment, of the present inventionwill be described referring to FIGS. 9A to 9D and FIGS. 10A and 10B.FIG. 9A illustrates the configuration of a defect inspection device 901in the fourth embodiment. In FIG. 9A, the defect inspection device 901comprises: a stage device including a test piece holder 902 which holdsa test piece in a test piece chamber 907 and a test piece holder rest917 which holds the holder; and a probe stage 906 including a probe unit933. A test piece is secured on the test piece holder 902. Since thetest piece is thin, however, it is not shown in FIG. 9A for conveniencefor drawing. For inspection on test pieces, an electro-optical device904 (which can be considered as a charged particle device), such as SEM(Scanning Electron Microscope) or FIB (Focused Ion Beam) device, havingion pumps 944 is provided. The electro-optical device 904 is installedon the enclosure of the test piece chamber 907 so that theelectro-optical device 904 is opposed to the test piece holder 902.Roughly approximated probe image acquiring devices 910 are provided inproximity to the electro-optical device 904. A charged particle beam(electrons or ion beam) is radiated from the electro-optical device 904toward the test piece holder 902 for observing the surface of a testpiece and the movement of probes 903.

One of the roughly approximated probe image acquiring devices 910 isprovided on the upper face of the enclosure of the test piece chamber907 in proximity to the electro-optical device 904. Each of the imageacquiring devices 910 comprises a probe roughly approximating opticalmicroscope and a CCD camera for acquiring images. The image acquiringdevices 910 are capable of observing the way the probes 903 are roughlyapproximated to a test piece and acquiring it as image information. One910A of the roughly approximated probe image acquiring devices 910 isvertically installed, and the other 910B is horizontally installed sothat both the image acquiring devices 910 are disposed crisscross. Thiscrisscross disposition makes it possible to observe the probes 903 notonly from above but also sideways, and the state of rough approximationcan be grasped with reliability. At this time, the image acquiringdevices 910 are so constituted that the magnification of the imageacquired sideways is higher than the magnification of the image acquiredfrom above. This is because of the following: in measurement, first,rough approximation is carried out by the roughly approximated probeimage acquiring device 910A positioned above. Thereby, the probes 903are horizontally brought closer to one another. At this time, aplurality of the probes 903 must be captured into a rough approximationimage. In rough approximation by the image acquiring device positionedsideways, the probes 903 are moved down and brought closer to the testpiece while the sideways rough approximation image is being viewed.Thereafter, the probes 903 are brought into contact with the test piecewhile the state of focusing on the tips of the probes 903 and the testpiece is being checked using the electro-optical device 904. If thedistance between the probes 903 and the test piece is short in sidewaysrough approximation, the time required to bring the probes 903 close tothe test piece using the electro-optical device 904 can be shortened.For this reason, the magnification of the rough approximation imagecaptured sideways is made higher than the magnification of the roughapproximation image captured from above.

The stage device comprises: the test piece holder 902 which holds a testpiece; a test piece stage 950 on which the test piece holder 902 isplaced; a large stage 949 on which the test piece stage 950 is placed;and a base 948 on which the large stage 949 is moved. The stage deviceis installed on the side face of the test piece chamber 907 through aface plate 971. The face plate 971 is installed on the test piecechamber 907 through a guide coupling board 971 a and a guide 971 b usingrollers, as illustrated in FIG. 10A. The upper drawing in FIG. 10A is atop view, and the lower drawing is a side view. As illustrated in FIG.10B, the stage device is pulled out along the guide 971 b when the stagedevice is maintained or the probe unit is replaced. The guide blocks 948a installed at the lower part of the test piece chamber 907, illustratedin FIG. 9A, are used to position the stage device relative to theelectro-optical device 904 in the vertical direction. Further, when thestage device is pulled out of the test piece chamber 907, the guideblocks 948 a guide the stage device. A sliding member 948 b is bonded tothe upper faces of the guide blocks 948 a which sliding members areeasily slidable between the guide blocks and the underside of the base948.

The probe stage 906 comprises: the probe unit 933 having probe holders931 for holding the probes 903; a probe unit base 934 which holds theprobe unit 933; and a probe unit stand 935 which connects the probe unitbase 934 to the large stage 949.

The probe unit 933 comprises x, y, and z tables (not shown), and iscapable of the probes 903 in the three-dimensional directions.

The base 948 is fixed on the face plate 971 by a fixing member 947. Thetest piece chamber 907 is provided with a test piece replacement chamber908 and a probe replacement chamber 909.

The face plate 971 is provided with feedthroughs for transmitting thefollowing signals from the outside of the test piece chamber 907:signals for controlling the operation of the x, y, and z tables of theprobe unit 933; and signals for controlling the operation of the x, y,and z tables 961, 962, 963, and 963 a of the test piece stage 950.

The interior of the test piece replacement chamber 908 and the interiorof the test piece chamber 907 are connected to each other through a gatevalve 921. The interior of the test piece replacement chamber 908 isconnected to DP (Dry Pump) 952, and vacumized. Thus, with the test piecechamber 907 kept in vacuum, the test piece holder 902 with a test pieceheld thereon can be replaced by a transporting means 929. FIG. 9A isdepicted as if the test piece replacement chamber 908 were connected tothe right side face of the test piece chamber 907, for convenience fordrawing. In actuality, the test piece replacement chamber 908 isprovided on the side face of the test piece chamber 907, positioned onthis side of FIG. 9A. This is for test pieces to be easily placed on thestage device located under the electro-optical device 904, asillustrated in FIG. 10A.

The probe replacement chamber 909 is provided on the upper face of theenclosure of the test piece chamber 907, in addition to theelectro-optical device 904 and the roughly approximated probe imageacquiring device 910A. The probe replacement chamber 909 is provided inproximity to the roughly approximated probe image acquiring device 910A.The interior of the probe replacement chamber 909 and the interior ofthe test piece chamber 907 are connected to each other thorough a gatevalve 923. The probe replacement chamber 909 is connected to TMP (TurboMolecular Pump) 951 and the DP 952 joined therewith, and is vacuumized.With the test piece chamber 907 is kept in high vacuum, the probe unit931 is replaced by a replacing means 955.

The test piece chamber 907 is connected with TMP 911 through a gatevalve 953, and the TMP 911 is in turn connected to DP 912. The enclosureof the test piece chamber 907 is supported on a frame 925 indicated byalternate long and short dash line.

A controller 913 and another controller 913A are provided. Thecontroller 913 comprises a probe unit control unit and a stage controlunit, and the another controller 913A controls high vacuum processing bythe TMP 911 and the DP 912. The controller 913A also controls the TMP951 and the DP 952.

The defect inspection device 901 further comprises a display device 914having an image display unit 915 and an image display control unit 916.Operation signals for the probes 903 and the stage device, from theimage display control unit 916, are transmitted to the probe unitcontrol unit and the stage control unit. The probe unit 933, stagedevice, and large stage 949 are thereby controlled.

The defect inspection device 901 further comprises CAD WS 981 having animage display unit 982 and an image display control unit 983. The CAD WS981 is connected to the display device 914, and transmits CAD image datato the display device 914 as required.

Before a probe is replaced, the y table and the x table of the probeunit 933 are moved to a predetermined position (e.g. rear end), and thez table is moved to a predetermined position (e.g. upper end).

The test piece stage 950 is moved so as to display the following on theimage display unit 915 for displaying image information from theelectro-optical device 904: a region on the test piece to be measured,that is, a region with which the probes 903 are to be brought intocontact. While the probes 903 and the test piece are viewed, the x, y,and z tables of the probe unit 933 are operated to bring the probes 903into contact with the region on the test piece to be probed.

In the present invention, there is no special limitation on the drivingdevices for the probes 903 and the stage device. However, a drivemechanism using piezo element, DC motor, or ultrasonic motor, forexample, is used for the drive mechanism for the probes. Pulse motor, DCmotor, ultrasonic motor, or the like is used for the drive mechanism forthe stage device.

Hereafter, description will be given to the constitution and operationof the major elements of the inspection device.

1. Constitution and Operation of Major Elements of Inspection Device

(1) Stage Device

FIGS. 9B, 9C, and 9D are detail drawings of the stage device. The stagedevice comprises the large stage 949 and the test piece stage 950.

(a) Test Piece Stage 950

The test piece stage 950 comprises the y table 962, x table 961, and ztable 963 and 963 a, and each table is moved in the y, x, or z directionby the drive mechanism. Since the test piece stage 950 is provided witha driving means for movement in the z (vertical) direction, thefollowing advantage is brought: the test piece stage 950 is moved downin the z direction before the large stage 949 and the test piece stage950 are moved in the x and y directions. Thereby, mechanicalinterference between the test piece 902 a and the tip of the electrongun 904 can be avoided. When the fourth embodiment is actually used tocarry out SEM observation, the following advantage is brought: the testpiece stage 950 is moved up in the z direction, and thereby the workingdistance between the tip of the electron gun 904 and the test piece 902a can be reduced. As a result, the spatial resolution of SEM can beenhanced. In the fourth embodiment, the driving means for movement inthe z direction is incorporated into the test piece stage 950. Instead,it may be incorporated into the large stage 949 or both of them. Inthese cases, the same effect is obtained.

The movement of the y and x tables 962 and 961 is accomplished bydriving ball screws by DC motors placed in the test piece chamber 907,and they are guided by cross rollers (not shown). As illustrated in FIG.9C, the movement of the z table 963 is accomplished by driving a DCmotor 963 b installed in the z table 963 a and thereby driving a ballscrew 963 e by shafts 963 c and 963 d through bevel gears 963 g and 963h. The z table is guided by cross rollers (not shown). As illustrated inFIG. 9A and FIG. 9B, the test piece holder 902 and the test piece 902 aare fixed on the test piece holder rest 917 installed on the z table963. Therefore, the test piece 902 a is moved in the x, y, and zdirections with respect to electron beam. The z table 963 has ameasuring position, test piece replacement position, and probereplacement position. The measuring position is a position in which theprobes 903 are brought into contact with the test piece 902 a. The testpiece replacement position is a position lower than the measuringposition, and the probe replacement position is a position at a furtherlower level. BY using these positions, collision between the test piece902 a and the probes 903 is prevented when the probes 903 or the testpiece 902 a is replaced. When these operations are performed, accurateand reproducible movement can be accomplished by taking the followingprocedure: measuring elements, such as linear scale or encoder, areprovided in the test piece stage 950, and the moving distance isquantitatively measured. FIG. 9B and FIG. 9C illustrate examples of theinstallation positions of the measuring elements. With respect to the xtable 961 and the y table 962, linear scales can be installed asillustrated in FIG. 9B. The upper drawing in FIG. 9B illustrates a sideview, and the lower drawing illustrates a top view taken along the lineAA′. The linear scales comprise mirrors 961 a and 962 a installed on thex table 961 and the y table 962, and measuring elements 961 b and 962 b.The moving distance of the z table 963 in FIG. 9C can be measured byinstalling an encoder 963 f on the shaft 963 c. In this example, thefollowing items are used for measuring the moving distance: an encoderwhich measures the rotation angle of a DC motor with respect to the ztable 963, and linear scales with respect to the x table 961 and the ytable 962. Instead, with respect to all of them, encoders may be used orlinear scales may be used. Or, a combination of them may be used.

To carry out SEM observation, a test piece 902 a attached to the testpiece stage 950 ought to be grounded via the test piece stage 950 and/orthe test piece chamber 907. This brings an advantage of prevention ofthe influence of electrical noise and charge-up arising from SEMobservation. On the other hand, to carry out measurement of electricalcharacteristics of a test piece 902 a, the test piece 902 a ought to beelectrically insulated from the test piece stage 950 and the test piecechamber 907. This brings an advantage of prevention of the influence ofelectrical noise from carrying out the electrical characteristicsmeasurement. Also, to prevent affection of charge-up, the electron beamemitted from electron gun of the electro-optical device 904 ought to beblanked. In the present invention, the electrical characteristics oftest pieces 902 a are measured. Therefore, the following effect issimilarly obtained: test pieces 902 a can be prevented from beinginfluenced by electrical noise or charge-up arising from SEMobservation. For electrical insulation, for example, the followingprocedure can be taken: as illustrated in FIG. 9D, an insulatingmaterial 918 is placed between the test piece holder rest 917 and the ztable 963. The holder rest 917 which holds the test piece 902 a isconnected to a cable 920. The cable 920 is led through the fixing member947 and the face plate 971 to outside of vacuum, and led to a groundterminal through a changeover switch 919. With this constitution, theinfluence of noise or charge-up can be prevented by connecting the testpiece 902 a to ground by the changeover switch 919 during SEMobservation. The following can be implemented by connecting the testpiece 902 a to an electrical characteristics measuring device, not toground, by the changeover switch 919: measurement of electricalcharacteristics, for example, the value of absorption current of thetest piece 902 a, can be carried out without the influence of noise fromthe test piece stage 950 or the test piece chamber 907.

Further, in the fourth embodiment, the following constitution may beadopted: a guard electrode and a ground electrode are provided in theprobe holders 931 and the test piece holder rest 917; and signalsdetected at the probes 903 and the test piece 902 a are led to outsideof vacuum. This produces the effect of enhancing the electricalinsulation for the probes 903 and the test piece 902 a.

(b) Large Stage 949

As illustrated in FIG. 9A and FIG. 9B, the large stage 949 comprises they table 965 and the x table 964, and is moved in the y direction and inthe x direction by driving devices (not shown). The test piece stage 950is driven as is placed on the large stage 949.

As illustrated in FIG. 9A, on the large stage 949, the probe unit 933constituting the probe stage 906, the probe unit base 934 which supportsthe probe unit 933, and the probe unit stand 935 are placed. The probeunit 933 is moved in the y direction, x direction, and z direction. As aresult, the probe holders 931 supported on the probe unit 933 are moved,and the probes 903 held at the tips of the probe holders are moved inthe y direction, x direction, and z direction.

The large stage 949 is moved on the base 948, and the test piece stage950 is moved on the large stage 949. The electro-optical device 904,roughly approximated probe image acquiring device 910A, and probereplacement chamber 909 are provided in parallel on the upper face ofthe enclosure of the test piece chamber 907. Therefore, the movingmechanisms can move the test piece 902 a and the probes 903 to theroughly approximated probe image acquiring potion, SEM observationposition, and probe replacement position. That is, the moving mechanismscan move the stage device (the test piece stage 950 and the probe stage906) between the following positions: any position in the verticaldirection with respect to the roughly approximated probe image acquiringdevice 10; any position in the vertical direction with respect to theelectro-optical device 904; and any position in the vertical directionwith respect to the probe replacement chamber 909.

Therefore, the test piece 902 a and the probes 903 are moved between thefollowing positions: any position in the vertical direction with respectto the roughly approximated probe image acquiring device 910; anyposition in the vertical direction with respect to the electro-opticaldevice 904; and any position in the vertical direction with respect tothe probe replacement chamber 909.

One of the features of the present invention is that movement on thebase 948 can be carried out with high vacuum maintained. Adoption ofsuch a moving method makes it possible to roughly approximate the probes903 to a test piece 902 a and position them with accuracy. Furthermore,the moving method makes it possible to quickly and easily carry outthese operations. In replacement of a probe 903, the probe 903 can bequickly and easily replaced with another with high vacuum maintained.

Therefore, the moving mechanisms can perform the following operationwith high vacuum maintained: it can move the test piece 902 a and theprobes 903 from a position directly under the roughly approximated probeimage acquiring device 910 provided in parallel with the electro-opticaldevice 904 to a position directly under the electro-optical device 904.

(3) Scanning Electron Microscope (SEM)

This is an example of the electro-optical device 904. It is used as anobserving means for bringing the probes 903 into contact with a targetlocation on the test piece 902 a, and is disposed at the upper part ofthe test piece chamber 907. Vacuum evacuation is carried out by the ionpumps 944.

(4) Test Piece Chamber 907

The test piece chamber 907 comprises a lid and a test piece chamber caseas an enclosure. On a side face of the test piece chamber case, the base948 is installed to the face plate 971 with the fixing member 947in-between. The probe unit 933 is placed on the large stage 949 in thetest piece chamber 907, and the test piece replacement chamber 908 isinstalled on another side face. On the lid, the electro-optical device904, or SEM, roughly approximated probe image acquiring device 910, andprobe replacement chamber 909 are installed. The test piece chamber 907is fixed on a load plate installed on a vibration-free mount installedon the frame 925. The test piece chamber 907 is evacuated to vacuum bythe TMP 911 and the DP 912.

(5) Optical microscope for Probe Rough Approximation, CCD Camera,Roughly Approximated Probe Image Acquiring Device

Test pieces 902 a whose electrical characteristics are to be measuredare, for example, semiconductor. Usually, the probes 903 are broughtinto contact with plugs connecting to source, drain, gate, or well. Thesmallest plugs are a few tens of nm in diameter, and SEM with highresolution is required for bringing the probes into contact with theplugs. However, when a semiconductor test piece is irradiated with anelectron beam, a problem arises: the test piece can be damaged by theelectron beam. In this case, it is preferable that the irradiation timeshould be shortened as much as possible. For this purpose, based on adetection value from the roughly approximated probe image acquiringdevices 910, the following operation is performed beforehand: aplurality of the probes are brought closer to one another in thehorizontal direction, and brought closer to the surface of the testpiece in the vertical direction. The image obtained by the opticalmicroscope for probe rough approximation and the CCD camera installed tothe microscope is displayed on the monitor of the image display unit915, and the above operation is performed while this image is viewed.

The magnification of the image on the monitor is set to several dozentimes so that the probes 903 will be brought closer to one another asmuch as possible and the probes 903 and the test piece 902 a can becaptured in one screen.

A light source is disposed adjacently to the optical microscope forprobe rough approximation. Observation under the optical microscope forprobe rough approximation and the CCD camera and introduction of lightfrom the light source into the test piece chamber are carried outthrough the observation window 939 illustrated in FIG. 9A.

(6) Test Piece Replacement Chamber 908

The test piece replacement chamber 908 is provided so as to replace atest piece 902 a without breaking the vacuum of the test piece chamber907, and is evacuated to vacuum by the DP 952. The test piecereplacement chamber 908 is separated from the test piece chamber 907 bythe gate valve 921. When a test piece 902 a is let in, the followingprocedure is taken: a male screw at the tip of a replacement rod whichis the transporting means 929 for the test piece 902 a and the testpiece holder 902 is screwed into a female screw provided in the testpiece holder 902 with the test piece 902 a is bonded thereto. The gatevalve 921 is opened, and the test piece holder is inserted onto theholder rest 917 installed on the upper face of the z table 963 of thetest piece stage 950. When a test piece 902 a is taken out, the aboveoperation is performed in reverse order. This shortens the time requiredfor replacing test pieces.

(7) Probe Replacement Chamber 909

The probe replacement chamber 909 is provided so as to replace probes903 without breaking the vacuum of the test piece chamber 907. It is forshortening the time required for replacing probes. The probe replacementchamber 909 is separated from the test piece chamber 907 by the gatevalve 923. The probe replacement chamber 909 is evacuated to vacuum bythe TMP 951 and the DP 952. The reason why the TMP 951 is used is asfollows: the probe replacement chamber 909 is big. Therefore, if it isevacuated only by the DP 952, the gate valve 923 is opened when theprobe replacement chamber 909 is under high pressure. As a result, ittakes a longer time to restore the pressure in the test piece chamber907 to the original value after replacement.

2. Control System

The various parts of the SEM, probe unit 933, and stage device arecontrolled by the respective control circuits and computers built in thecontroller 913. The SEM, probe unit 933, and stage device can beoperated through either of the respective operation panels and the GUIon the monitor.

The controller 913 comprises the stage control unit for controlling theposition of each stage, and the probe control unit for driving the probeunit 933 independently of the stage device. The image control unit 916includes a secondary electron detector control unit, the control unitfor an electron beam irradiation optical system, and the like. Inaddition, a computation processing unit is provided with a function ofdisplaying the probe holders 931, the test piece 902 a, the state inwhich the probes 903 are in contact with the test piece 902 a, and thelike in the form of image. At this time, the computation processing unitdisplays images in combination with the control unit for the displaydevice 914.

Further, by operating the operation screen on the image display unit,operation signals are supplied to the probe unit control unit and thestage control unit through the image display control unit. Thereby, theprobe unit 933 and the stage device are moved and positioned. Aside fromthis, the probe unit 33 and the stage device may be moved and positionedusing an operation panel having a joystick.

(1) SEM

An electron beam produced in the electron gun is applied to the testpiece 902 a through a convergent lens and an objective lens. Secondaryelectrons produced at the test piece 902 a are detected by the secondaryelectron detector. The resulting signals are subjected to variedelectrical processing in the display, and the image of the test piecesurface is displayed on the monitor of the image display unit 915 of thedisplay device 914.

(2) Probe Unit 933

Signals for controlling the operation of the x, y, and z tables of theprobe unit 933 are supplied as follows: as illustrated in FIG. 9A,signals from the control circuit 913 in the frame 925 are supplied tothe probe unit 933 in the test piece chamber 907 via the feedthroughsinstalled in the face plate 971 of the stage device.

Input signals supplied to a test piece 902 a through the probes 903installed on the probe holders 931, and output signals obtained from atest piece 902 a are inputted/outputted as follows: the signals areinputted or outputted to, for example, a semiconductor parameteranalyzer through three-layered coaxial hermetic connectors installed onthe test piece chamber 907.

(3) Stage Device

Signals for controlling the operation of the x, y, and z tables 961,962, 963, and 963 a of the test piece stage 950 of the stage device aresupplied as follows: signals from the control circuit in the frame 925are supplied to the test piece stage 950 in the test piece chamber 907via the feedthroughs installed in the face plate 971.

3. Display Device 914.

The display device 914 displays rough approximation images obtained atthe roughly approximated probe image acquiring devices 910 and the imageof the contact of the probes 903 with the test piece 902 a obtained atthe electro-optical device 904. More specific description will be given.The display device 914 displays a probe operating screen and anoperating procedure screen which shows the details of the operatingprocedure.

Following the operating procedure shown in the operating procedurescreen, the user positions the test piece 902 a and the probes 903 withaccuracy while viewing a rough approximation image and a probing image.

4. CAD Workstation (CAD WS) 981.

The defect inspection device 901 comprises the CAD WS 981 provided withthe image display unit 982 and the image display control unit 983. TheCAD WS 981 is connected to the display device 914, and transmits CADimage data to the display device 914 as required.

With the above-mentioned constitution, as in the procedure described indetail in connection with the first embodiment, the following operationcan be performed: while CAD information is viewed, the test piece stage950 is moved. Thereby, a region on the test piece 902 a to be measured,that is, a region with which the probes 903 are to be brought intocontact is displayed on the imaged is play unit 915 for displaying imageinformation from the electro-optical device 904. While the SEM image andthe CAD image of the probes 903 and the test piece 902 are viewed, theprobe unit 933, that is, the probes 903 are moved in the x, y, and zdirections. Thereby, the probes 903 are brought into contact with theregion on the test piece 902 a with which the probes are to be broughtinto contact.

In the fourth embodiment, the accuracy of movement of the test piecestage 950 can be enhanced and quantified by incorporating linear scalesor encoders into the test piece stage 950, as illustrated in FIG. 9B.This produces the effect of CAD navigation being carried out moreaccurately.

With this constitution, EBAC measurement which is described in detail inconnection with the third embodiment can also be carried out. When EBACmeasurement is carried out, as described in detail with respect to thethird embodiment, the value of absorption current measured by the probes903 or the test piece 902 a is often very small. For this reason,detected signals can be influenced and deteriorated by noise. In thiscase, the following procedure can be taken instead of connecting thetest piece 902 a and the probes 903 directly to the electricalcharacteristics measuring device: a preamplifier is respectively placedin the wiring between the test piece 902 a and the probes 903, and theelectrical characteristics measuring device in proximity to the testpiece 902 and in proximity to the probes 903. Then, microcurrentdetected at the probe 903 and the test piece 902 a is amplified, andthen transmitted to the electrical characteristics measuring device.FIG. 10B illustrates a constitution for amplifying absorption currentsignals detected by the probes 903 through the preamplifier. In FIG.10B, a signal detected by the probes 903 is transmitted to thepreamplifier 1002 through a cable 1001. The signal amplified here isguided to outside of vacuum from a cable 1003 through a hermeticconnector provided in the face plate 971. The cable 1003 is fixed on amounting seat 1005 by a relay terminal 1004. The preamplifier 1002 isalso installed on the mounting seat 1005. The mounting seat 1005 is inturn fixed on the probe unit base 934. The place of this fixation is notlimited to the probe unit base 934, and it may be fixed on any otherfixing seat as long as the fixing seat can be disposed in proximity tothe test piece and the probes. As mentioned above, FIG. 10B illustratesthe constitution of the preamplifier for amplifying signals from theprobes. To amplify signals from test pieces, the same constitution canbe adopted. Depending on whether EBAC measurement is to be carried outor not, signals from the probes or the test piece may be connected to ordisconnected from the preamplifiers. As illustrated in FIG. 10B,instead, a probe stage mounted with a preamplifier and a probe stage notmounted with a preamplifier may be prepared beforehand and selectivelyutilized. This produces the effect of EBAC measurement being carried outwith the influence of noise on microcurrent being reduced.

The fourth embodiment is provided with a function of updating thedisplayed CAD image in accordance with change in the fields of viewembracing the SEM image and the EBAC image by the same method asdescribed with respect to the first embodiment. Therefore, with a defectinspection device of the fourth embodiment, a burden on the equipmentuser is significantly lessened during probing.

In the fourth embodiment as in the third embodiment, only one probe 903is used in defect inspection in some cases and a plurality of probes arerequired in other cases. For example, when a plurality of pieces ofwiring are inspected for break or on like occasions, these pieces ofwiring can be inspected at a time by probing a plurality of plugs.

In FIG. 9A, the defect inspection device of the fourth embodiment looksto use only two probes 903. In actuality, however, more than two probesare used sometimes.

In the fourth embodiment as in the first embodiment and the thirdembodiment, the SEM image and the CAD image or the EBAC image and theCAD image can be displayed in superimposition (not shown). Thereby, theequipment users' convenience is further enhanced when the user finallymanually brings probes in contact and estimates the location of a break.

In the fourth embodiment as in the first embodiment, an arrow indicatingan area can be displayed over the CAD image at low magnification (notshown). Thereby, the equipment users' convenience can be enhanced whenthe user manually moves the probes.

In the fourth embodiment, SEM images and EBAC images can be obtained.These images can be displayed on the image displaying means 915 providedto the display device 914. At this time, the operating screen of theimage displaying means 915 provided to the display device 914 candisplay all or any of the SEM image, EBAC image, and CAD image. If theoperating screen is provided with icons for changing the screens,various type of display can be implemented. For example, arbitraryimages can be selectively displayed, all displayed, or displayed insuperimposition.

In the fourth embodiment, the display device 914, CAD workstation 981,and other control units are constituted as separate computers. As in thefirst embodiment, they may be integrated and constituted as a singlecomputer.

As mentioned above, the introduction of CAD navigation produces theeffect of remarkably enhancing the users' convenience when bringingprobes into contact with probing positions.

In the above description of the present invention, semiconductor istaken as an example of test piece. To measure local electricalcharacteristics, the device of the present invention may be used for themeasurement of other test pieces than semiconductor. For example, thedevice may be used for the measurement of the local insulationresistance of a magnetic head or the like.

The defect inspection device based on a combination of probes and acharged particle beam system, proposed here, has a configurationsuitable for the introduction of CAD navigation. The present inventionremarkably enhances the users' convenience when bringing probes intocontact with probing positions.

The present invention enhances the equipment users' convenience whenusing a charged particle beam system with probes incorporating CADnavigation. That is, the present invention makes it possible to providea probe navigation method and device and a defect inspection devicewherein probing can be easily carried out regardless of the equipmentuser's level of skill.

1. A charged particle beam apparatus comprising: a plurality of probes,each of the probes having a tip for contacting a sample; a probe drivingunits for driving each of the probes independently; means for placing asample that moves in X, Y and Z direction; said means for placing asample is provided with a driving unit that moves the plurality ofprobes and the means for placing a sample in unison; an electro-opticaldevice to irradiate the sample with a charged particle beam and toobtain a second charged particle image by detection of a second chargedparticle beam resulting from irradiation of the sample; a computerconnected to CAD image storing means for storing layout pattern of thesample, and a displaying unit for displaying the second charged particleimage and a CAD image corresponding to field of view of the secondcharged particle beam image.
 2. The charged particle beam apparatusaccording to claim 1, further comprising an inputting unit for enteringinformation; wherein said computer links the second charged particleimage and the CAD image based on a positional information inputted fromthe inputting unit.
 3. The charged particle beam apparatus according toclaim 1, wherein said computer links the respective magnificationinformation between the second charged particle image and the CAD image.4. The charged particle beam apparatus according to claim 1, wherein,when magnification of the second charged particle image is changed, saidcomputer calculates amount of movement of the means for placing thesample from a positional information specified on the CAD image and thepresent positional information of the means for placing the sample, saidmeans for placing a sample moves the calculated amount.
 5. The chargedparticle beam apparatus according to claim 1, wherein, when a field ofview of said second charged particle image changes, said displayed CADimage is updated to new CAD image corresponding to new filed of view ofthe changes second charged particle image.
 6. The charged particle beamapparatus according to claim 1, wherein the CAD image is superimposed ondisplayed second charged particle image.
 7. The charged particle beamapparatus according to claim 1, first CAD image and second CAD imagewith higher magnification than that of the first CAD image are displayedon the displaying unit, and an indicator for indicating the second CADimage on the first CAD image.
 8. The charged particle beam apparatusaccording to claim 1, wherein said first CAD image is an overall view oflayout pattern on the sample.
 9. The charged particle beam apparatusaccording to claim 1, further comprising: a first image processing unitfor processing the information of the CAD image; and a second imageprocessing unit for processing the second charged particle image. 10.The charged particle beam apparatus according to claim 1, said means forplacing a sample provided with a driving unit comprising: a first stagehaving a sample placing surface; and a first stage driving unit fordriving the first stage; a second stage on which the probe driving unitand the first stage are built; a second stage driving unit for movingthe second stage; and a controlling unit for controlling the probedriving unit, the first stage driving unit, and the second stage drivingunit.